In the course of manufacturing or assembling various manufactured goods it is often desirable to orient and feed components or precursors of the goods from a supply source to a downstream processing station at which the components or precursors may be further processed or assembled with other components. Typical manufacturing operations to which the invention is applicable are blow molding operations and trimming operations. At one point e.g., in the manufacture of mass produced blow molded objects such as plastic containers for beverages or other liquids, so called “preforms” are fed from a container or hopper to a downstream station or stations where the actual blow molding operations will occur. In order to carry out this operation in a rapid and accurate fashion it is necessary to order these preforms into a single line of successive units, all of which are appropriately and identically oriented, and which are then directed in single file rapidly moving fashion to the further station(s) such as those of a blow molding operation. Basically therefore one starts with a collection of preforms in a large hopper or container and processes these through an orienting and feeding station as to end up with an output flow of single file preforms, all properly oriented for further processing at downstream stations.
An example of a well known blow molding preform to which the invention is applicable, is an elongated generally cylindrical plastic preform, one end of which is a threaded neck portion for the ultimate blow molded container, and the other end of which extends from the opposed end of the cylindrical object as a narrower and heavier tubular portion which during the blow molding operation will be softened and enlarged into the ultimate container. Such preform further includes an encircling handling disc between the threaded neck portion and tubular portion which has a larger diameter than the remaining portions of the preform, the disc serving to facilitate handling of the preforms.
In the past it has proved very difficult to orient and feed elongated objects of the foregoing types in rapid fashion. Many prior art devices have relied upon complex rotating tables and the like having deflecting surfaces which orient the objects as they spin and centrifugally move on the table to which they are fed, so as to enable the objects to exit from a peripheral point of the table properly oriented. These devices are unfortunately not capable of rapid and accurate processing of the objects. Accordingly a need exists for apparatus which are capable of orienting and accurately and rapidly feeding such elongated objects in the manner of interest to the manufacturer.
In our abandoned U.S. patent application Ser. No. 10/353,638, filed Jan. 29, 2003, and published on Jan. 29, 2004 under US-2004-0144618-A1, we disclosed apparatus and methods for rapidly orienting and feeding generally cylindrical, substantially identical elongated objects which are broadly characterized by having a maximum transverse diameter Y. In accordance with that invention first and second continuous conveying belts are provided having input and output ends for cooperatively conveying such objects toward a downstream processing line. The belts are mounted so that their respective conveying surfaces are movable in a common parallel direction. The facing edges of the conveying surfaces of these belts are spaced from one another to define a uniform gap between them of a dimension less than Y. The conveying surfaces reside and are movable in planes which are upwardly sloped away from the gap. The surfaces thereby define a zone converging downwardly in the direction of the gap. Object input means are provided for depositing the then unoriented elongated objects at the input ends of the conveying belts and object output means at the distal ends of the belts receive the objects, which are then oriented, and direct them toward the downstream processing line. In accordance with the orienting feature of that earlier invention means are provided for moving the belts in a common direction, but at different respective speeds. In consequence the unoriented elongated objects deposited at the input ends of the belts are rotated by contact with the differentially speeding belts as the objects descend into the converging zone and become supported at the gap and conveyed by riding on the edges of the moving belts which border the gap. The objects as they descend become oriented in positions of gravitationally maximum stability relative to the mode of support, these positions being commonly characteristic for the particular objects.
The said objects are typically fed to the input ends of the belts from a supply hopper or other container via a supply belt on which the objects are deposited as substantially a single layer of randomly oriented objects for feeding to the moving conveying belts as a collection of mutually spaced such objects. The conveying belts are preferably flattened closed loops, the conveying surfaces of which are defined at the uppermost sides of the loops. The conveying belts are preferably moved at a differential speed in the range of 110% to 180% (i.e., one belt moves at a speed which is 1.1. to 1.8 times faster than the other). The difference in speed is more generally such in relation to the path length for conveyance that the objects can be rotated as they descend in the converging zone to the desired new stable positions. The apparatus and method may include features for removing objects at the output ends of the conveying belts which have not properly descended in the converging zone to achieve the desired stable support positions at the gap. These mis-oriented objects are recycled to an upstream point for further treatment in accordance with the invention.
The prior art invention is diagrammatically illustrated in FIGS. 1 and 2 in which FIG. 1 is a perspective view of such apparatus and FIG. 2 is an end view of the apparatus. The apparatus 10 shown is particularly useful for orienting and feeding preforms of the type that has been previously discussed. These preforms are intended for orienting and feeding to a downstream processing point where they will be subjected to a blow molding process in order to produce a container of the type commonly used for various liquids such as large plastic beverage containers and the like. These preforms 12 are fed from an input bin (not shown) via a supply input belt 14. The representative preform 12 is a moldable plastic product which is well known. It is a unitary structure having an enlarged threaded portion 16 from which extends a tubular portion 18 which is of reduced diameter and which is heavier than the portion 16. As has previously been discussed the threaded portion 16 will ultimately form the neck of the blow-molded container, whereas the tubular portion 18 will form the hollow body of the container. The preform 12 is seen to be generally cylindrical and its largest transverse diameter is defined at portion 16.
The preforms 12 are next deposited upon a feed input belt 20, which is operated by a motor 22 which actuates a timing belt 24 for belt 20. A guard 26 surrounds the timing belt. Preforms 12 are deposited upon the surface 25 of input belt 20 substantially as a single layer so that they become relatively spread out as separated objects as they proceed to the remainder of apparatus 10. One of the guide walls 21 bordering belt 20 has been partially broken away to better show this. As seen in FIGS. 1 and 2 the preforms 12 descend down a chute 28 whereupon they reach the feed orienting and conveying belts 30. In the embodiment shown in FIGS. 1 and 2 the conveying belts 30 comprise a first belt 32 and a second belt 34. The latter can comprise a single wide belt, but in this embodiment actually comprises two commonly driven sub-belts 36 and 38.
Belts 32 and 34 are driven by separate motors and gearing arrangements, one such motor and gear box being shown at 40. The speed of these motors is separately controlled with the objective that the belts 32 and 34 are driven at different speeds. The preferable differential speed is in the range of approximately 110 to 180 percent. The belt 34 as mentioned consists of two sub-belts 36 and 38 in order to give it a greater width. This is necessary since the objects being fed from chute 28 proceed from the outer side of belt 34, which preferably has a sufficient width at its upwardly facing conveying surface to accommodate the approximate length of the elongated objects even when crosswise, thereby preventing the objects from falling off. The opposed first belt 32 is provided with a guard edge 33 (shown in FIG. 2 and partially in FIG. 1) to prevent the preforms from inadvertently falling from that side of the moving belts 30.
A basic feature of the prior art invention as seen in FIGS. 1 and 2 is that the belts 32 and 34 have their conveying surfaces 35 and 37 in planes which are sloped upwardly away from the space or gap 42 which is defined between the adjacent edges of the parallel moving belts. These sloping surfaces provided by the belts therefore define a converging zone 43 wherein the preforms 12 gravitationally descend toward the gap 42. The angle of convergence for this zone is generally in the range of 90° to 120°, but may vary depending upon the objects being oriented, and other factors such as the rates of belt advance. The two surfaces bounding the zone of convergence need not have an identical slope angle with respect to the gap. The preforms 12 are objects which are generally cylindrical and have a maximum diameter Y defined by the threaded neck portion 16. The gap 42 between the belts 32 and 34 is of a dimension which is less than Y but greater than the smallest transverse diameter of tubular portion 18 of preforms 12. Gap 42 can be varied by an adjusting screw 45. Because of the differential speed of movement of the conveying surfaces of the belts 32 and 34 the preforms 12 as they descend in converging zone 43 are rotated by contact with the belts on each side of the object, and as they drop toward and into gap 42 they achieve their characteristically gravitationally most stable position. In this case that position is one wherein the heavier tubular portion 18 slides downward into and through the gap 42 and wherein the enlarged neck portion 16 rides upon the adjacent edges of the two conveying surfaces 35 and 37. The preforms 12 are therefore now properly oriented and continue downstream.
A deflecting surface 44 is provided at the output ends of the belts 30 to deflect any preforms which are not properly oriented and seated in the gap 42, so that these deflected objects proceed to the right in the sense of FIG. 1 onto a recycle conveyer 46, which feeds these recycled objects back to the belts 30 at an upstream point via return chute 48.
From the output end of the apparatus 10 the now oriented preforms 12 proceed via an output chute or channel 50 where they are advanced to a further station as for example the aforementioned blow molding station (or associated stations) at which heating and blow molding of the preforms 12 may occur.
The prior art apparatus discussed, while being generally effective in its use, was found by the inventors to be commercially unacceptable in that during operation preforms which did not descend properly into the gap between the conveying belts and become correctly seated therein, would frequently become impossible to deflect from the conveyed stream at the output end thereof and would thereby impair the apparatus operation. Lengthy investigation revealed that what was happening, as illustrated in the schematic of FIGS. 3 and 3A, was that the preform 60 shown there was becoming frictionally locked due to the edge 62 of disc 64 effectively locking with the lateral edge 66 of the adjacent belt 37. Thus a solution was sought which is the subject of the present invention.